In the electronics industry, there is a constant demand for electric devices, such as integrated circuits ("IC's") or semiconductor chips, to be produced less expensively and in smaller dimensions. One way to increase productivity of such electric devices, and thereby reduce their unit cost, is to increase the test speed of the devices by testing a plurality of them at the same time.
It has become a test technology standard to place a number of electric devices to be tested on a test tray and position them so as to be engaged by a test head plate having a number of corresponding test contactors. One device is placed on a seat of a carrier module, and each carrier is typically provided with a pair of device seats. A number of modules are then positioned on a tray so as to be in vertical alignment (either above or below) with a test head plate. Each module is aligned with a corresponding test contactor so that when either the test tray or the test head plate are moved in a vertical direction relative to one another, the contactor engages the device positioned within the carrier.
The contactor is provided with a number of test pins or electric leads which come into electrical communication with the leads of the electric devices to be tested. The test system is provided with a test signal generator for supplying a test signal to the device, and with a signal comparator for analyzing the results of the test. Based on such results, the electric devices are transferred to another location in the test process and sorted for proper handling.
Thus, in order to increase the volume of electric devices that can be tested in the manner described above during a given period of time, it is desirable to maximize the efficiency of the contact test assembly, including primarily the test contactor and the carrier containing the electric devices. However, such standard electric device test systems described above suffer from a number of disadvantages. First, the contactors for engaging the electric leads of the devices are specially made for engagement with a device of a particular configuration. Furthermore, the structure of such contactors in a conventional test system is complicated since they utilize, other than contact pins, a mechanical drive mechanism which selectively engages and disengages each lead of the device to be tested in accordance with an external power source such as compressed air. One example of such complicated, specially made contactors is disclosed in U.S. Pat. No. 4,370,011.
Secondly, such specially made contactors are typically not available as "off-the-shelf" items and are therefore relatively expensive. Third, because of the relatively complicated nature of the mechanical structure of the contactors, they are typically large in size. Therefore, it is difficult to assemble a number of such contactors in a confined area in order to increase the density of test contacts. Therefore, the number of electric devices that can be tested at one time is limited. Fourth, such conventional contactors are not highly reliable because of the complexity of their mechanisms, especially when attempts are made to assemble a large number of such contactors on a test head plate.
Additionally, the size and configuration of standard electric chips is rapidly changing. For example, some of the high speed ICs have very short signal leads, instead of the relatively longer leads used in the conventional dual in line ("DIP") type package. In order to test such short leads, conventional contactors cannot be used since secure engagement with the electric devices to be tested is prevented by the interior walls of the carrier modules. Furthermore, in conventional test systems using trays, carrier modules placed on a tray are used only for a certain predetermined type and shape of electric device. If the outer shape of the electric device to be tested changes, the carrier modules must also be changed. Thus, it is very expensive to have a large number of carrier modules of various configurations. Moreover, it is time consuming to change the carriers every time a different chip is to be tested.
Thus, there is a serious need in the electric device test industry for a contact assembly which can overcome the problems described above.